1. Field of the Invention
The present invention relates to methods and apparatus for configuring femtocell devices for performing handoffs in a communication system.
2. Description of the Related Art
Femtocell devices are small base stations designed for home or small business use. Femtocell devices provide cellular coverage having a small (<200 m) range, and are designed to provide cellular coverage in the home or office. The typical femtocell device connects to Security Gateway or Softswitch over an Internet Protocol (IP) connection, such as a Digital subscriber line (DSL) or broadband cable connection. The femtocell devices are intended to plug into a DSL or a cable modem using a standard Ethernet cable.
Handoffs of users from femtocell devices to the macro-network which contains the femtocell devices is usually performed using standard inter-operability messaging. If the femtocell device is using the same air interface technology as the macro network, the handoff is performed in the following procedure. The user, i.e., a mobile note, monitors pilots from the macro-network and reports the pilot strength measurement to the femtocell device serving an area where the mobile note is located. If the mobile node ventures outside the range of the femtocell device (leaves the house, for example), the femtocell device will determine, based on pilot strength measurement reports received from the mobile, that a handoff to the macro-network is needed. Using configured parameters, the femtocell device associates the pilot pseudo-random (PN) number with the sector_identity (ID) of the macro base station serving the area to which the mobile node is moved, and forwards the sector_ID to a softswitch using the standard handoff messaging. The softswitch then forwards the sector_ID to a Mobile Switch Center (MSC), which, using the sector_ID, contacts the appropriate macro base station to arrange the handoff.
Similar messaging can be used for inter-technology handoffs. In this case, the mobile node may receive pilots from the macro-network, but the mobile node will not report these pilots to the femtocell device, because the femtocell device is operating with a different technology. In this situation, the mobile may initiate a handoff by sending a message to the femtocell device that is destined for the macro-network, such as a Registration Message. Again, the femtocell device must be provisioned with the sector_ID or some type of identification for the macro base station, so that when the message is forwarded to the softswitch, it can determine which macro base station to contact.
The disadvantage of the contemporary inter-technology handoff process is that the femtocell devices need to be configured with some type of identifier (sector_ID, IP address, etc.) for the macro base station that is covering the area that the femtocell device is deployed in. Since a single macro base station may encompass a large area, many femtocell devices may need to be configured with this information at the time of deployment. Additionally, once configured with the information of the macro base station, the femtocell device can not move to a new location (i.e. into the coverage area of another macro base station) without being re-configured.
Such manual configurations are costly and can lead to errors in deployment. Therefore, there exists a need for a method by which femtocell devices can be dynamically configured, so that inter-technology handoffs to macrocell networks can be accomplished, even if the femtocell device moves to a new location served by a different macrocell base station.